Units of Action, or Units (sometimes also called beats), were first suggested by Konstantin Stanislavski as a means of helping actors determine the through line or super objective of a role. A unit is a discrete piece of action in a play-text, marked by a significant change in action. This could be a change in what the characters already onstage are doing or trying to do i.e. a change in their objective, a new character entering the scene or those already onstage exiting.
Units are also used by writers and dramaturges as a means of analyzing text for editing purposes. Dividing text into units makes it more manageable and thus easier to edit.
The use of units of action was based around the emotional construct of the character. If emotional memory is to be used how can that be interpretated through voice. The process can make the actor change emotion all together if he/she finds the line in itself can not justfy the emotion